Republican senators led by Ted Cruz introduced a bill aimed at funding President Donald Trump’s border wall. The WALL Act would give the government $25 billion toward construction and would be funded by what supporters call “loopholes” in the current immigration system, according to the Hill.

“I have long called for building a wall as a necessary step in defending our border and stopping the flow of illegal immigration into our country. The overwhelming majority of Texans and Americans want to see the border secured,” Cruz said in a press release. “The WALL Act would fully fund the border wall by closing existing loopholes that provide illegal immigrants with federal benefits and tax credits, without affecting the benefits and tax credits used by Americans.”

The proposal was introduced by four Republican lawmakers, including Cruz, a senator from Texas, Senator Jim Inhofe of Oklahoma, John Kennedy from Louisiana, and Mike Rounds, a senator from South Dakota.

Senator Rounds said that he believed the funding was necessary in order to protect Americans from terrorists, gang members, and drug dealers who cross the border illegally.

The proposed $25 billion would be funded by increasing fines on those who cross the border illegally. It would also create a minimum penalty for people who stay beyond their visa time limit. The bill would also eliminate loopholes that immigrants can use to obtain federal benefits, requiring work-authorized Social Security numbers for anyone who wants to claim refundable tax credits.

Rounds said that the latter provision was necessary because right now only the child needs a Social Security number to claim credits under the Child Tax Credit. He also claims that immigrants can claim Earned Income Tax Credits because Social Security numbers prior to 2003 did not distinguish between work-eligible and non-work eligible numbers.

The bill would close these two loopholes.

Senator Kennedy said that he believes that anyone who receives food stamps or other earned benefits needs to prove that they are a U.S. citizen. To that end, the bill would require recipients to formally verify their citizenship.

The proposal comes as a government shutdown looms over the funding of the border wall, though it may be unlikely that the WALL Act will gain any ground in Congress. House Speaker-designate Nancy Pelosi says that the debate should be postponed for a year to avoid the shutdown, but she has stated that she would outright reject Donald Trump’s demand for $5 billion towards border security.